1. Field of the Invention
This invention relates to the nonrecovery coking of coal, and more particularly to an improved method of operation of a nonrecovery coke oven battery for coking of coal.
2. Description of the Prior Art
The practice of producing metallurgical coke by a nonrecovery coking process was for many years all but abandoned in favor of the byproduct coking process in which the coke gas and other chemicals were recovered and/or refined for further use. The high cost of constructing and operating such byproduct coking plants has resulted in renewed interest in the nonrecovery process in recent years, however, and substantial improvements have been made both in the operating efficiency and the control of pollution from nonrecovery ovens. Examples of modern high speed sole flue type nonrecovery coke ovens now in operation in the United States are disclosed in Thompson U.S. Pat. Nos. 4,287,024 and 4,344,820. Such ovens are generally referred to as Thompson ovens, and the present invention is an improved method of operation of a Thompson coke oven battery.
Difficulty has been encountered in consistently obtaining a uniform coking rate throughout all the ovens in a Thompson coke oven battery constructed in accordance with the above patents. Such ovens may have a coking chamber of up to fifty (50) feet in length and up to twelve (12) feet in width, and may be filled to a depth of up to five (5) feet or more with green coal at the beginning of a forty-eight (48) hour coking cycle. Normally eight (8) or more adjacent ovens are connected through a common combustion tunnel to a single stack, and no means other than adjustable damper valves for varying the amount of combustion air admitted through inlets in the oven doors, the sole flues, and/or the common tunnel, are provided for varying the draft to the respective ovens. Each oven preferably has two systems of sole flues beneath the coking chamber and since the uptakes leading from one of the two flue systems under each of two adjacent ovens were connected through a common connector to the combustion tunnel, adjusting the combustion air to one oven necessarily effected the draft to the adjacent ovens.
In the past, combustion air to the ovens, flues and common tunnel has been regulated manually. An operator, relying on experience and a knowledge of the coking cycle, would look into the oven crowns and the sole flues, or at the exhaust at the top of the stack and, based upon the observed conditions, make adjustments to the damper valves used to control the air flow. This procedure would be repeated periodically say every one or two hours, throughout the coking cycle.
Copending application Ser. No. 587,742 now U.S. Pat. No. 5,114,542, discloses an improved Thompson coke oven battery and its method of operation in which a draft regulating valve is connected in the conduit which provides gas flow passage from each sole flue system to the common combustion tunnel. The position of the respective valves is adjusted from a central control station, relying on pressure sensors to indicate desired draft changes to regulate the draft applied by the stack through the sole flue systems to the individual ovens. That application also discloses the use of a damper valve at the top of the stack, which damper valve may be adjusted to regulate the draft applied through the common combustion tunnel to all the ovens in the battery. An operator at a remote control station, relying on signals from pressure sensors in various locations in the respective ovens, periodically adjusted the position of the respective draft regulating valves and/or the stack damper valve to maintain the draft in the individual ovens at the desired level to thereby control the coking rate in all ovens in the battery. The present invention is an improved method of operation of the coke oven battery disclosed in said U.S. Pat. No. 5,114,542, the entire disclosure of which is incorporated herein by reference.
It is a primary object of the present invention to provide an improved nonrecovery coking battery and method of its operation for the high speed coking of coal at a more uniform coking rate throughout the ovens in the battery.
Another object is to provide such a coking installation including improved means for automatically controlling and regulating the draft supplied to the individual coking ovens in a battery of ovens connected to a common stack.
Another object is to provide such a coking installation including means for automatically sensing the temperature at various locations in the individual ovens in a battery and for adjusting the draft to the respective ovens in response to the sensed temperature.
Another object is to provide such an installation and a method of its operation, which enables an increased yield of high quality coke from a charge of coal.